Thread trimmer for buttonhole sewing machines



Oct. 24, 1933. J. H. 'p u 1,931,556

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed March 21, 1952 3Sheets-Sheet 1- Fig.1.

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06L 24, 1933. H. P|KUL 1,931,556

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed March 21, 1932 3Sheets-Sheet 2 lnvenTon- \JosephHPiKu! Anys.

b zwa @MW Oct. 24, 1933. J. H. PIKUL 1,931,556

THREAD TRIMMER FOR BUTTONHOLE SEWING MACHINES Filed March 21, 1932 3Sheets-Sheet 3 7 Fig.5.

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Patented Got. 24, 1933 PATENT OFFICE THREAD TRIMMER FOR BUTTONHOLESEWING MACHINES Joseph H. Pikul, Troy, N. Y., assignor to The ReeceButton Hole Machine Company, Boston,

Mass, a corporation Application March 21,

16 Claims.

invention relates to thread-trimming devices for buttonhole-sewingmachines by which the leading from the under side of the k at thecompletion of the buttonhole, and the stay cord, if one is used insewing the buttonhole, are out close to the work at the completion ofthe sewing operation, and the invention has particular reference to suchthread-trimining devices in which the cutting of the thread is accornrished a er the have been opened. One of the objects of the invention isto provide improvements in thread-cutting devices of this type by whichthe tl.. 'ead or threads leading from I the under side of the work canbecut closeto the work without danger of cutting or injuring thebuttonhole stitches or the fabric or other materiai in which thebuttonhole is sewed;

Most buttonhole sewing machines are con- I structed so that thebuttonhole. is sewed with the direction of the length thereof, thesesuperposed.

lines of stitching lying on the face ofthe goods and thus producinga ribefiect.

' ting any of the threads forming the fly bar of the In some buttonholesewing machines the thread-trimming device which trims-the threadunderneath the work at the completion of the butter mic is provided witha thread-cutting edge situated and operating substantially in the planeof the under face of the work. I

it is one of the objects of the present invention to provide animprovement in thread-cutting devices of this type which will operate toseparate the work from the cutting edge of the thread cuttersufficiently so that the thread may be trimmed close to the work withoutdanger of cut buttonhole. This is provided for by means which I operatesafter the work clamps have been opened but before the thread is cut tolift the work sufficiently so that the stitches of the fly bar will becleared from the cutting edge of the thread cutter. I

In order to give an understanding of the invention I have iilustrated inthe drawings some selected embodiments thereof which will now bedescribedafter which the novel features will be pointed out in theappended claims.

v Fig. l is a side view of a portion of a buttonhole sewing machineembodying my invention;

In the sewing of of Maine 1932. Serial No. 600,081

Fig. 2 is a top plan view of the work clamps; Fig. 3 is a View of thework-lifting plate; Fig. 4 is a section on the line 4-4, Fig. 2;

Fig. 5 is an under side view of the clamp plates and thread-cuttingmechanism;

Fig. 6 is a fragmentary view showing the means for operating the threadtrimmer;

Fig. '7 is a section on the line 7-7, Fig. 5;

Fig. 8 is a section on the line 8--8, Fig. 2 showing the position of theparts at the completion of the buttonhole sewing but before the work isunclamped; I

Fig. 9 is a similar view showing the position of the parts after thework is unclamped and has been raised. and just' before the thread iscut;

Fig. 10 is a sectional view similar to Fig. 7 but showing the partsafter the clamps have. been raised and the work-lifting plate has beenactuated to lift the work. I

Fig. 11 is a view showing the thread-cutting elements;

Fig. 12 is a view of a fly bar buttonhole.

The sewing machine shown in Fig. 1 is of. that type which comprises abed frame 1 carrying work-holding means in which the work 2 is heldduring the sewing operation, and which also I comprises astitch frame 3carrying the stitch forming mechanism, said stitch-forming mecha. nismhaving a feeding movement relative to the work-holding means during thesewing operation and a further relative movement after thestitch-forming mechanism comes to rest to. carry the parts fromstitching position to buttonholecutting position. I .I

The work-holding means is mounted on the usual clamp plates 4 that areremovably carried by the'bed 1. Said work-holding means includes theroughened plates or mats 5, 6 that are secured to the clamp plates 4,and clamping feet 7, 8 which clamp the work against the mats 5' and 6.These clamping feet are carried by clamp arms 9 pivoted to the clampplates 4 at 10 as usual in buttonhole sewing machines of this type. Theclamps 7 and 8 are operated by the usual mechanism which causes themtoclose onto the work before the sewingon the buttonhole begins and holdsthem clamped against the work during the sewing operation and whichreleases them at the completion of the sewing operation.

The stitch-forming mechanism is of the usual type which comprises aneedle 11 operating from above the work and carrying a needle thread 65,

and loopers or their equivalent operating beneath the work and carried.by a rotary turret 12 which many respects to the thread cutter shown in,my

' clamp plates 4. The cutting element 19 is in avvay'to receive saidblade 19 when it' is in its under thread 32 and stay cord 33 p clampingfoot 8. is alsoin the form of a blade having a cutting is journalled inbearings 13, 14 carried by the lower portion 15 of the stitch frame 3,said turret carrying at its upper end the usual throat plate 16 which isprovided with the sewing opening 17 through which the needle 11 operatesand through which the under thread 32 and stay cord 33 are led to thesewing point.

The needle l'l'is mounted in the usual needle bar 18 which is mountedboth for reciprocation on the stitch frame 3 and for turning movementtherein as usual in buttonhole sewing machines of this type.

In the sewing machine herein shown the necessary relative movementbetween the stitchforming mechanism and work-holding means is secured bya movement of thestitch frame 3 back and forth on the bed frame 1, andas will be understood from those familiar with buttonhole sewingmachines of this type the stitchforming mechanism and work-holding meanshave a relative feeding movement during the sewing of the buttonhole andwhen the sewing operation is complete the stitch-forming mechanism comesto rest with the needle raised as indicated in Fig. l and the stitchforming mechanism and work-holding means then have a further relativemovement to carry the work from stitching to buttonhole-cuttingposition, which is the dotted line position shown in Fig. 1. During suchfurther relativemovernent a length of is drawn through the throat plate16, such lengths of under thread and stay cord lying underneath thework.

The thread cutter herein shown is similar in co p ending applicationiderial No.- 585,0'l3,' filed January 6, 1932. Such thread cuttercomprises two cutting elements-19 and 20 which are coaxially pivoted ona stud 21 carried by one of the the form of a blade having a cuttingedge 22 and situated beneath the clamping foot 8 and having its upperface flush with the work-supporting surface of the mat 6, said mat beingout inoperative position. ihe upper face of the blade 19 thus forms partof the work supporting' surface against which the work is clamped by theThe thread-cutting member 20 edge 23 which normally extends transverselyto the line of stitching'when the thread cutter is in its inoperativeposition.

Both of the blades are provided with hub'portions through whichthe pivotstud 21 extends,

the hub portion of the blade 19 being indicated at 24 and that of theblade 20 at 25. These two hub portions are superposed one on the other.

of' the work. Saidoutter is actuated by means similar to that shown inmy copending applica tion Serial No. 535,073.

Each of the cutter elements is provided with a tail portion 26 betweenwhich is situated a cam member 2'? carried by a rock shaft 28 journalledin one of the clamp plates 4. This rock shaft extends below the clampplate and on its lower end it is provided with an arm 29 having adepending portion 39 that is adapted to be engaged by an upstanding armSlthat is carried bythe turret 12.

- In these buttonhole sewing machines it 'willbe The thread cutter isthus situated directly be-' neath'the work and normally or during thesewbuttonhole-cutting position and at the same time drawing out throughthe throat plate a length 32 of under thread and a length 33 of staycord which extends from the last stitch to the throat plate.

'After the parts have been carried into buttonhole-cutting position,which is the position shown in Fig. 8, the clamps are opened as shown inFigs. 9 and 10 and after the clamps are opened the rotation of theturret 12 actuates the thread cutters 19 and 20 to cut the lengths 32,33 of thread extending from the under side of the work to the throatplate.

In sewing a fiy bar buttonhole 34, such as shown in Fig. 12, the barportion 35 of the buttonhole is formed by two overlying rows ofstitching situated in the center line of the buttonhole, one line ofstitching being formed at the beginning of the sewing operation and theother at the completion of the sewing operation. The superposed lines ofstitches present a rib-like projection on the under face of the goodswhich eX- tends from the last stitch to the buttonhole slit.

When the parts are being carried from stitching to buttonhole-cuttingposition and the lengths of under thread and stay cord 32, 33 are beingdrawn through the throatplate, the strain on the thread tends to pullthework down against the cutting blades.

As stated above, one of the objects of the present invention is toprovide for manipulating the Work at the time that the lengths 32, 33 ofthread are cut so as to obviate any danger that the cutters will damageeither the goods or the stitches constituting the bar 35 of thebuttonhole. This is done by providing means for separating the goodsslightly from the work-supporting surface after the clamps '7 and 8 havebeen released and before the lengths 32, 33 of thread are cut, suchraising movement being sufficient to ensure that the stitches formingthe bar. 35 are separated sufficiently from the path of movement of thecutting edges of the thread cutters 19 and 20 so that'the thread lengths32, 33 will be out without any injury to the stitches forming the barportion 35 of the buttonhole.

- Foraccomplishing this I provide a Work-lifting plate which is situatedunderneath the work and between the latter and the clamp plates 4 andwhich is lifted from the clamp plates slightly after the work clamps 7,8 have been released and before the thread is actually cut.

Such work-lifting plate is indicated at 36 and the buttonhole iscompleted at the'end of the sewing operation the throat plate 16 will belocated between the two extensions 39 and 40 as shown in Fig. 2.

Means are provided for raising the free end of the work-lifting plate 36after the work clamps '7 and 8 have been released. In the constructionherein shown this work-lifting movement of the plate 36 is derived fromthe cutting movement given to the thread-cutting blades. Said plate isshown as having a rounded projection ll on its under face which, whenthe cutting blades are in their open position, occupies an opening orrecess {L2 in the cutting blade 20, the plate 36 at such time lyingflatly against the upper face of the cutting blade 20. When the cuttingblades receive their initial thread-cutting movement a pressure of thewall of the opening 42 against the rounded projection 41 will cam theprojection upwardly and force it out of the opening thereby raising thework-lifting plate 36, into the position shown in Figs. 9 and 19. Duringthe remainder of the thread-cutting movement of the blade 20 theprojection 41 will ride on the top of said blade and thus hold thework-lifting plate in its raised position. This raising of thework-lifting plate 36 lifts the work as shown in Figs. 9 and 10, suchlifting movement being suilicient to carry the stitches forming the barportion 35 of the buttonhole sufficiently above the cutting edges of thecutting blades 19 and 20 so that the thread lengths 32 and 33 may be cutclose tothe work without danger of injuring either the stitches 35 ofthe buttonhole or the goods.

When the thread-cutting blades return to their normal or open positionthe aperture 42 will be brought underneath the projection 41 and theresiliency of the plate 36 will cause the projection 41 to enter theaperture again and the plate 36 to resume its normal position lyingflatly against the thread-cutting blade 20 and with the ends 39' and i0lying against the Work-supporting surface.

I claim:

1. In a buttonhole sewing machine, in combina tion, stitch-formingmechanism, work-clamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of the sewing,thread-cutting mechanism operating beneath and in close adjacency to thework, means to actuate the thread-cutting mechanism after the clampshave released the work, and means operating subsequent to the release ofthe clamps but before the thread is out to separate the work from thethread-cutting mechanism.

2. In a buttonhole sewing machine, in combination, stitch-formingmechanism, workclamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of the sewing,thread-cutting movement between the work and the thread-cnt- I tingmechanism.

3. In a buttonhole sewing machine, in combination, stitclvformingmechanism, workclamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of the sewing,thread-cutting mechanism operating beneath and in close adjacency to thework, means to actuate the thread-cutting mechanism after the clampshave released the work, and means operating subsequent to the release ofthe clamps but before the thread is cut to raise the work from thethreadcutting mechanism.

4. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of the sewing,thread-cutting mechanism operating beneath and in close adjacency to thework, means to actuate the thread-cutting mechanism after the clampshave released'the' work, and means actuated by the thread-cuttingmechanism to produce a relative separating movement of the work and saidthread-cutting mechanism before the thread is cut,

5. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end ofthe sewing,thread-cutting mechanism operating beneath and in close adjacency to thework, means to actuate the thread-cutting mechanism after the clampshavereleased the work, and means actuated by the thread-cutting mechanism toraise the work from the latter before the thread is cut.

6. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of thesewing,thread-cutting mechanism comprising a pair of cutting blades operatingin planes parallel to the work and in close adjacency thereto, means togive said blades their thread-cutting movement after the clamps havereleased the work, and means to produce a relative separating movementbetween the work and said blades subsequent to the release of the clampsbut before the thread is cut.

'7. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which. clamp the work during the sewingof the buttonhole and which release the work at the end of the sewing,thread-cutting mechanism comprising a pair of cutting blades operatingin planes parallel to the work and in close adja cency thereto, means togive said blades their thread-cutting movement after the clamps havereleased the work, and means to raise the work from the blades after theclamps have released thework and before the thread is cut.

8. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping-means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of the sewing,thread-cutting mechanism comprising a pair of cutting blades operatingin planes parallel to the work and in close adjacency thereto, means togive said blades their thread-cutting movement after the clamps havereleased the work, and means actuated by the thread-cutting movement ofthe blades to raise. the work from the blades after the clamps have beenreleased and before the thread is cut.

9. In a buttonhole sewing machine, in cornbi- 10. In a buttonhole-sewingmachine, in combination, stitch-forming mechanism, work-clamping meanscomprising clamp plates against which the work is clamped, twoco-operating thread-trimming elements situated on top of the clampplates and beneath the work, means to actuate said elements to cutthread, and means actuated by said thread-trimming elements to separatethe work therefrom before the thread is cut.

11. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewing onthe buttonhole and which release the work at the end of the sewing, athroat plate through which the thread is led to the work, saidstitch-forming mechanism and work-clamping means having a relativemovement at the completion of the sewing to carry the parts fromstitching to buttonhole-cutting position and to draw out a length ofthread through the throat plate, a thread cutter for cutting the threadbetween the throat plate and the last stitch, means to actuate thethread cutter after the clamps are released, and means to separate thework from the cutter prior to the cutting of the thread.

12. In a buttonhole sewing machine, in combination, stitch-formingmechanism, means to produce a relative movement between thestitchforming mechanism and the work, a threadtrimming knife situatedtransversely to the line of stitching and which is placed between thethread to be trimmed and the work by such relative movement, said knifeoperating in close adjacency to the work, means to actuate thethreadtrimming knife, and means to separate the work from said knifebefore the thread is cut.

13. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means, thread-trimming means normallyin contactwith the under surface of the work, and.

means to produce a relative separating movement between the work and-thetrimmingmeans just prior to trimming the thread.

14. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewingand which release the work at the end of the sewing, thread-trimmingmeans in'contact with the under surface of the work during the sewing,and means to produce a relative separating movement between saidthread-trimming means and the work after the sewim operation but beforethe threads are cut,

15. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewingand release the work at the end of the sewing, thread-trimming means incontact with the under surface of the work during the sewing, and meansto separate the work from the thread trimming means after the clamps arereleased but before the thread is cut.

16. In a buttonhole sewing machine, in combination, stitch-formingmechanism, work-clamping means which clamp the work during the sewing ofthe buttonhole and which release the work at the end of the sewing, saidwork-clamping means comprising clamp plates, and clamping feetpivotaliy. mounted thereon, thread-cutting mechanism operating beneathand in close adjacency to the work, means to actuate the threadcuttingmechanism after the clamps have released the work, and means operatingsubsequent to the release of the work but before the thread is cut toraise the work from the clamp plates.

JOSEPH H. PIKUL.

